there may be good manhwas just as there are good mangas
An example of a good manhwa for me is faeries' landing which is a manhwa from tokyopop
the art is good just as the storyline is good and has funny parts

after you get over the drawing style (in comparison to manga that i'm more used to), most of the manhwa stories are quite entertaining. some parts drag, some stories have disappointing ending and some had almost the same plot (strong glutton girl who can't beat the guy she likes but can send a whole gang of delinquents to the hospital).
i've read and finished some manhwa, just got bored in some parts but i liked them. Red Lion, He's Dedicated to Roses, Hot Blooded Woman were good. I'm still reading Saver, Love in the Mask and Absolute Witch (i'm sure they're korean and they are really good). Waiting for the updates really takes a lot of my patience =)

Well there are some good k-mangas, but for the most part I find most to be too shojo or bishonen for me, the hero or heroine or friends are beautiful and rich or talented but the bad guys or side characters are totally ugly and retarded, and the plot is somehow predictable. BORING.

Just think it like this, J-Manga are quite good that people have made dramas out of them, K-Dramas are actually much better that mangas have been made out of them. If I want to read drama, I watch Korean but if I want to read manga, Japan is much better.

PS:
Great Manga made into drama - Hana Yori dango - http://www.onemanga.com/Hana_Yori_Dango/
Great K-drama - Jewel in the Palace
'Shipwrecked Manhwa' is pretty good from what I read in the first few chapters although it seem to resemble Ouran Host Club.

I find that many Korean manhwa artists tend to pay more attention to drawing very detailed characters. Not saying Japanese artists don't pay as much attention, some notable examples being Yuki Kaori, Peach-Pit, and Hino Matsuri. But more than 4/5 of the manhwa I've seen are the type that are very detailed as far as artwork is concerned. You don't see manhwa with a casual type of drawing very often.

Another thing I've also noticed is, some (not all) manhwa don't have the smooth transition from panel to panel that you see in Japanese manga. Like, the connection between one scene and the next is not consistent enough to make it look natural.

With that said, I'm not saying I don't like Korean manhwa. Some of them are really good. It's a good thing you don't see a lot of the cliche pathetic idiotic female characters you would find in abundance in many (not all) Japanese shoujo manga. Those characters always make me wanna say: Oh please, grow some backbone and braincells will ya? Korean manhwa heroines are much more independent in comparison. However, some of these very independent heroines are too feisty to the point of being completely obnoxious. That I don't appreciate anymore than I do the idiot type.

I won't make any comparison of manhwa and manga in terms of plots because that would just be unrealistic. No matter what country it comes from, a good story is a good story, and a bad one, still bad.

Edit: forgot to mention the thing about the names, sometimes I can't get used to Korean names.